Byron holbeook



(Specimens) B. HOLBROOK.

PREPARING TAN BARK.

No. 284,738.. -Patented Sept. 11, 1883.

WITNEEEEE @JNITED STATES P TENT Oriana.

BYRON HOLBROOK, OF KENOSHA, \VISOONSIN, ASSIGNOR OF TWVO-THIRDS TO CHARLES WV. ALLEN AND NATHAN R. ALLEN, JR, BOTH OF SAME PLACE.

, PREPARING TAN-BARK.

SPBCIFICATION forming 'part of Letters Fatent No. 284,738, dated September 11, 1883.

Application filed May 9, 1883, (Specimeus.)

To all whom, it may concern.-

Be it known that I, BYRON HOLBROOK, of Kenosha, in the county of Kenosha and State of WVisconsin, have invented certain Improvements in Processes for Preparing Tan-Bark,

of which the following is a specification.

My invention relates to the preparation of dry tan-bark for use in tanneries; and the in vention consists in crushing the dry bark be- IO tween rolls in such a manner as to break up the cellular structure of the bark, so as to enable the tannin contained in the cells to be more effectually and quickly extracted.

Figure 1 is a perspective view, and Fig. 2 a

I 5 transverse vertical section of a machine designed for treating the bark in accordance with my method or process.

It is well known to those engaged in tanning that it is difficult, if not absolutely impossible, to extract all the tannin from bark when used in the ordinary way in tanneries; and as tan-bark is becoming constantly more difficult to obtain in the required quantities, and consequently more expensive, it is very desirable to have some means by which the tannin may be more effectually, and also more quickly, extracted" from the bark, and to accomplish this is the object of my present invention. Ordinarily the bark is simply ground in a'bark-mill, and then leached in vats; but when so used the cellular structure of the bark is not destroyed or broken up, and the consequence is that, even though the bark be soaked or leached foralong time,more or less of the tannin is still retained in the cells of the bark, and is thereby lost. In order to obviate this difiiculty,Icrush the bark by passing it between rolls, so arranged as to subject it to great pressure, thereby effectually crush- 40 ing every particle of the bark in such a manner as to break up and destroy its cellular structure, thereby opening the cells, so that the water may have more ready and free access to them, and thus combine with and 5 thoroughly extract the tannin therefrom. It is obvious that this may be done by means of two or more rolls, and that the machine may be constructed in various w. ys.

In the accompanying drawings I have illustrated a simple form of machine for this purpose which I have found to operate well, though I do not limit myself to the use of any particular style of machine for carrying out my invention, which consists,primarily,in the process or method of preparing or treating the bark while in a dry state.

The machine in this "instance consists of two rolls, A and B, mounted in asuitable frame, the roller B being mounted in fixed bearings, while the roller A is mounted in adjustable bearings, having set-screws e or equivalent means for regulating the pressure at will. These rolls carry at one end gear-wheels O D, while the roll A has at its opposite end a gearavheel, G, with which engages a pinion, I, secured to a counter-shaft, H, which carries at its opposite end a pulley, J, to receive a belt from the engine or drivingshaft, and by which motion is imparted to the two rolls. A wheel, E, is secured to the opposite end of roll B, and arranged to engage with a wheel, F, secured to the end of a feed-shaft, L, which extends lengthwise through ahopper, M, secured above the rolls, asclearly shown in Figs. 1 and 2. One of the rolls, A, is provided at each end with a radial flange, 0, which fits into a corre sponding recess on the ends of the-other roll, 13, the object of which is to prevent the bark from working or being crowded out from be tween the rolls at their ends. Underneath each roll I arrange a scraper, T, which extends the entire length of the face of the roll, for the purpose of removing all adhering particles of bark and gummy matter, with which they would otherwise soon become coated. These scrapers may be made adjustable.

As shown in Fig. 2, the feed-shaft consists of a rectangular metallic bar,'the angles of compress and crush the bark. I prefer to use rolls of comparatively small diameter, for the reason that they will operate more effectually, as a smaller portion only of their surfaces will act at any one instant upon the bark that may be'between them.

In preparing the bark I usually first grind it in a bark-millin the usual manner, and then pass it between the rolls in the manner described, care being taken to have the rolls so adjusted as to apply a very strong pressure to the particles of bark as they pass-between the rolls. The result of this operation is that the bark will pass from the rolls in the form of a thin sheet or thin flakes, with its cellular structure completely broken up or destroyed, so that it is in a condition to readily yield up its tannin far more efiectually, and in much less time than when prepared in the ordinary manner or merely ground.

While I prefer to grind the bark before passing it between the rolls, I do not consider that as absolutely necessary, because the same result may be produced more or less effectually by crushing the slabs of bark without first grinding them.

By this method of preparing tan-bark not only can the tannin be more fully extracted and in much less time, but it can beprepared at the tannery whenever required, or can be prepared and shipped, stored, and kept ready for use at any time.

I am aware that it has been proposed to pass slabs of wet bark between a series of rolls for the purpose of preparing the liquid extract, and also that it has been proposed to press ground tan-bark into cakes for shipment, and I do not claim either of these methods of treating the bark as my invention; but,

Having thus fully described my invention, what I claim is 1. The herein-described method or process of preparing tan-bark for use, which consists in crushing the dry bark and reducing it to thin flakes by passing it between rolls under heavy pressure, substantially as and for the purpose set forth.

2. As a new product, dry tan-bark reduced to thin flakes by great pressure, substantially as herein described.

BYRON HOLBROOK.

Witnesses:

J. F. MORIN, J AMES OAVANAGH. 

